Strange power factor registered with e Shelly EM

Hi, I recently installed a Shelly EM with two 50A clamps, one positioned on the input from the grid and one on the return from the photovoltaic inverter.

I think the clamps are mounted correctly because it registers:

  • In input from the grid, a positive power when I consume more than that produced, otherwise negative
  • In return from the photovoltaic inverter, a positive power if it produces, otherwise 0

The problem concerns the value of the PF:

  • At the grid input, PF is almost always negative, whether the power from the grid is positive or negative. At night when the photovoltaic is at 0 and with the house in standby I register about 50W positive but always a negative PF, very close to 0 though. Among other things, 50W seems few to me, considering that the router and the home automation server are working.
  • in return from photovoltaics, the PF value is 0 if it does not produce, otherwise -1 (but with positive power…)

Can you help me interpret these data? They seem wrong to me.

Thank you

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